I want to ask for the community's help regarding upgrade of a 120mm case fan for a Razer Core X EGPU. There is a standard 3-pin fan connector on the Thunderbolt 3 controller within the case. I have tried connected an EK Vardar 4-pin PWM fan as well as a NOCTUA NF-F12 PP2000 (3-pin configuration). What happens is the new fan will not consistently start up. Sometimes the fan will spin, other times, the fan will just be stalled and have small jerky movements. After 3-4 power cycles or PC reboots, the replacement fan could start spinning. As soon as I replace the Razer case fan, the OEM 3-pin fan will start up every time consistently.
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The Razer OEM fan is unmarked so there is not voltage or amperage ratings. Given the behavior with the replacement fans, has anyone else had a similar experience and if so, how did you resolve it? I realize the upgraded eGPU fan may not result in better temperatures, but I am just curious now. I have contacted Razer but their official line is "We don't give out technical specifications of our products (referencing fans and 3-pin connector power ratings).

If nothing else, this experience should help the community with others who may want to upgrade. Thanks for any insights or links that may shed light on this issue.

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While trying to upgrade the fans, I accidentally stripped one of the screws holding the 120mm case fan in place. Razer places a thread-locker on so be aware of this if you are loosening for the first time. After countless orders of screws in which the shipping cost vastly more than the contents, I have determined that the replacement screws are M3x20mm. These can be ordered from C S Enterprises out of Foxworth, MS.

Still no new info on what kinds of 3-pin 120mm fans will work, but in case someone else messes up a screw, here is my small contribution.

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Has anyone been able to remove the front black cover in the metal cover shroud of the razer core x ? note it is shown here that it is removable and I have seen it being held in place by a few torx screws.
Has anyone tried to see if you can mount fans in those screw holes (mounting fans instead of the cover plate pic. bottom left ) let me know if it aligns with fan mounts and if mounting a 240mm rad is possible.

thanks

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For non-blower style GPUs, consider reversing the orientation of the included 120mm cooling fan. I noticed that rather than expelling hot air from my Dual-Fan GPU, it was taking air from the outside into the case. This means there is cold air coming in from both the left and right side leading to air stagnating inside the Core X's case and warmer temperatures. I reversed the orientation of the Razer fan to expel hot air outside the enclosure.

The 120mm Case Fan is likely a Sunon EEC0251B3-0000-A9. The "Sunon" brand is written on the fan body. It is a 120 x 120 x 25mm fan with a 3-pin connector. The specifications for max-rated are: 0.161 amps, 12V, 1.9 watts. It is rated at 75 CFM, 2200rpm, 34dBA, and 0.16 in of H2O.

As stated in the earlier post, this is the only fan that has been able to consistently spin up. Based on Noctua's FAQ on replacing NAS fans and the possible difficulties that can be encountered due to custom fans and specifications such as start voltages, it is likely that this Sunon fan has some specialized start voltage which causes other fans (4-pin PWN and 3-pin to fail); either it is too high or low for EK Vardar and Noctua fans.

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According to the data sheet of the fan i'm successfully using, its Voltage range DC (V) is 5-13.2, Input power (W) is 1.44, Input current (A) is 0.12.
I'm not sure what all this means but i thought i'd let you know.

@spicybitterness, thank you for taking the time to share your information on the Be Quiet fan. I will follow suit and add some information as well. The co-worker to whom I sold my eGPU enclosure was able to get his Noctua 120mm, 3 pin fan to start without issue. I asked for his specs and the exact model is the NF-A12x25 FLX model. He did not use any of the LN or ULN adapters. The power ratings for this fan are (listed as maximums):
12V, 1.68watts, and 0.14 amps.

The key take-away here is that based on spicybitterness and my colleague's experience, it seems that in order to get a replacement fan to spin every time, it has to have a low starting voltage. I noticed that the Be Quiet website advertised the Silent Wings 3 as having a low starting voltage due to its six coils. The NF-A12x25 also has 6 coils in its motor. Perhaps what was causing the other fans I tested before to error out and start inconsistently was the incompatible starting voltages.

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